Plastic pouches used to sterilize and store sterile items for dental and medical use have been available for many years. Such pouches often consist of two similarly sized rectangular sheets in face to face contact, sealed around their periphery. At the time the pouch is manufactured, only three edges are sealed, leaving an access opening to insert items to be stored at a later date. The fourth seal, to seal the access opening, is made after the item to be kept sterile has been inserted into the pouch. After the item to be stored is inserted in the pouch, and the pouch sealed, the item in the pouch is sterilized by steam autoclaving or by using another sterilizing gas such as ethylene trioxide (ETO). In either case, maintaining the item in a sterile state until use depends on the package being adequately sealed to prevent the entry of bacteria.
The three edge seals made at the time of manufacture of the pouch are usually made by applying heat and pressure along relatively narrow lines near the edges to be sealed. The fourth seal, made after the pouch is loaded, may also be a heat seal, but often heat sealing equipment is not available at the location where the pouch is loaded. In particular, many health care offices, including offices of both doctors and dentists, do not have the equipment for making heat seals; hence, for these locations other sealing systems must be used to seal the pouch.
Pouches to be loaded and sealed where heat sealing equipment is not available are generally made to be sealed adhesively. Adhesively sealed pouches for this application are commonly made with one sheet overhanging the other in a manner similar to an envelope flap. The flap is covered with self-adhesive which, at the time the pouch is to be sealed, is folded over the access opening such that the adhesive covers the opening. So long as the two components of the pouch are flat sheets, such construction has been found to be satisfactory. However, the capacity of pouches made of flat sheets is somewhat restricted, and it would be desirable to have gussets or pleats in one of the sheets to allow the pouch to expand and thereby hold larger items. If pleats were to be included in prior art pouches, it would be found that there are three thicknesses of material at the pleat, which are difficult to seal with an adhesive covered flap. In order to create a seal at the pleat, the adhesive must seal to the edge of all three thicknesses of material, which is not likely to occur consistently. Hence, such a pouch would be considered to be unreliable as a container for sterile articles.